Andrew Millar has discovered key biochemical mechanisms through which plant respiration is adapted to cellular processes and harsh climates. He has identified how damage by lipid, oxygen and nitrogen radicals lower the efficiency of respiration. He has discovered how vitamin production is linked to respiration and how mitochondria signal their metabolic state to change plant defence gene expression. Millar has shown that the mitochondrial proteome response to plant stress involves specific and sequential changes in protein complex assembly, regulation of enzymes and selective chemical damage. His discoveries underpin our understanding of respiratory damage during plant cell ageing and disease.